CDKN1A and neoplasm: Consistent with this, we observed increased CDKN1A (p21), which is a tumor suppressor gene mainly expressed in the G2/M phase under p53 protein control during the cellular checkpoint for DNA damage.37 In a broad spectrum of tumors, including hematological malignancies, CDKN1A is repressed and is associated with poor prognosis.38 Reduction of MYB levels may also contribute to the cell cycle arrest observed in HEL cells, given its role in the G2/M transition through direct regulation of cyclin B1 expression in normal and neoplastic hematopoietic cells.39